3 Chest Examinations in Children

Transcription

1 3 Chest Exmintions in Children The chest film is the most frequently ordered peditric rdiogrphic exmintion. However, ecuse one looks t so mny chest rdiogrphs, fmilirity my crete flse sense of security rther thn expertise. A thorough, detiled, systemtic pproch to the rdiogrphic evlution is crucil for nyone deling with children. In this chpter we discuss the generl dignostic principles nd pproch; the specifics of chest exmintions for neontes nd infnts re reviewed in Chp. 4. This chpter lso stresses those res where the pproch to the peditric chest rdiogrph differs from the dult film [the 3 T s: technicl fctors, tues, nd trps i.e., ntomicl structures unique to kids; thnks to Dr. Moir Cooper, peditric rdiologist, (British Columi Children s Hospitl, Vncouver, Cnd)]. We present common pthologicl conditions s foil to the norml chest film (Fig. 3.1). Fig Norml inspirtory chest Frontl exmintion revels norml lung volume. The criteri for norml lung volume re: () less thn one-third of the hert is projected elow the hemidiphrgm; () the diphrgm is rounded, nd the sixth or seventh nterior ri (r) intersects the diphrgm; nd (c) the lungs re ir-filled (lck). This is properly positioned, nonrotted film s evidenced y (1) comprtive nterior ris equidistnt from the pedicles (p), (2) medil spects of the clvicles (cl) symmetriclly positioned, (3) the crin pproximtes the right pedicles (rrow), nd (4) no difference in ertion etween the two sides. The film ws tken with the ptient erect, s shown y the ir fluid level in the stomch (rrowhed) Lterl exmintion confirms norml ertion of the lungs. Note tht the verterl odies (v) get lcker s we go from superior to inferior. The ptient is slightly rotted s you cn see the ris on ech side (rrows)

2 16 3 Chest Exmintions in Children Technicl Fctors Technicl prolems in peditric rdiology re cused lrgely y uncoopertive children. The young ptients re not feeling well, the environment is strnge, nd they my s result e quite frightened. Preliminry evlution of the chest rdiogrph should ssess these technicl fctors: The degree of inspirtion: lung volume The position of the ptient: extent of rottion nd posture of the ptient How the film ws otined Adequcy of the exposure Lung Volume The rdiogrphic exmintion of the chest egins with frontl nd lterl roentgenogrphs tken fter deep inspirtion. The degree of inspirtion, i.e., the lung volume, generlly determines wht is seen on the film. The nswers to the questions in Tle 3.1 determine whether or not dequte lung volume is otined. If the child hs tken shllow reth, the hert my pper enlrged, the vessels my colesce to give flse impression of n opcity, especilly in the region of the ses nd hil, nd sometimes the rdiogrph hs hzy qulity due to the influx of lood nd lck of erted lung. Hyperexpnsion of the lungs pthologicl increse in lung volume or ir trpping is involuntry. The chnges of hyperexpnsion listed in Tle 3.1 should e visile on oth frontl nd lterl films. Figures demonstrte the differences etween the norml rdiogrph nd those in which inspirtion is either pthologiclly incresed or suoptiml. Cn you pick out the optiml rdiogrph? Position of the Ptient The position of the ptient is determined y rottion nd posture (lying, sitting, or stnding). The child s posture is importnt.when the ptient is supine, the vsculr supply to the upper nd lower loes is equl since grvity hs no effect. When the child is sitting or stnding, grvity plys significnt role, nd the upper-loe vessels re less distended thn the lower-loe vessels (one-third to two-thirds size). One cn determine n erect film y looking t the ir fluid level in the stomch nd t chnges in the pulmonry vsculture. Rottion of child is determined y the nswers to the questions in Tle 3.2. Figure 3.4 shows the prmeters tht determine rottion, while Fig. 3.5 exemplifies the posture of the ptient, showing supine nd erect films. Compre these figures with Fig To which side is the child rotted in Fig. 3.4 nd e? See Appendix 2. Tle 3.1. Determining lung volume: questions nd nswers (Figs ) Question How much of the hert projects elow the dome of the diphrgm on the frontl view? On the frontl view, re the domes of the diphrgm flt? Are the hemidiphrgms flt or verticlly oriented on the lterl film? Which nterior ri crosses the diphrgm on the frontl film? (Rememer tht the nterior ris move more thn the posterior ris on good inspirtion) On the lterl view, is there tringle of ir ehind the hert? Are the lungs lck or white on the frontl film? Answer More thn 1/3: expirtory effort; not enough ir in lungs Less thn 1/3: good inspirtory effort; norml mount of ir None: my e hyperexpnded; too much ir No, very domed: expirtory exmintion No, rounded: good inspirtory effort Yes, flt: good or my e too gret lung volume No, horizontlly oriented: expirtory effort Yes, verticlly oriented: good or possily incresed lung volume 3rd or 4th: expirtory effort 5th or 6th: inspirtory effort 7th or lower: good or possily too gret lung volume No: expirtory effort (except if lrge hert) Yes: inspirtory effort Blck: ir-filled, inspirtory White or gry: not ir-filled, expirtory

3 Position of the Ptient 17 c d Fig Expirtory chest Frontl film tken during expirtion, i.e., () more thn one-third of the hert projects elow the diphrgmtic mrgins (elow the dotted line), () hemidiphrgms re domed, nd the fourth nterior ri (r) crosses the diphrgmtic mrgin, nd (c) the lungs re not s well erted. The ptient is rotted, s shown y () symmetric comprle ris in reltionship to the pedicles nd () symmetric position of the clvicles note the right end of the clvicle (cl) is quite lterlly positioned Expirtory lterl film shows no posterior ir spce ehind the hert (compre this to Fig. 3.1) c e These three films re in vrying degrees of inspirtion: c is n optiml inspirtion; d is cceptle ut less thn verge with the 5th nterior ri t the diphrgm; e shows complete expirtion with lmost white-out of the lungs. It is importnt to pprecite the degree of inspirtion so one cn mke n ccurte determintion of ny pthology e

4 18 3 Chest Exmintions in Children c Fig Hyperexpnded chest rdiogrph Frontl view. The entire hert is projected ove the diphrgm, the hemidiphrgms re flttened, nd the lungs re quite lck yet the film is not overexposed. You know this ecuse you cn see the pedicles of the spine ehind the hert nd the peripherl vsculture (rrow) Lterl view. The hemidiphrgms re oliquely oriented (rrow), nd there is lrge ir spce () oth ehind nd in front of the hert. Rememer: hyperexpnsion is involuntry nd is cused y ir trpping. It must e seen on oth frontl nd lterl projections c, d Comprle drwings of the hyperexpnded lungs d

5 Position of the Ptient 19 c d Fig The rotted chest Schemtic drwing demonstrtes the signs of rottion symmetric clvicles, differences in ertion (not shown), hert projected over one hemithorx nd not the other, symmetric ris when relting the nterior ri to the pedicle Rotted chest s in. Note the child hs n opcity (rrow) in the lower right lung field. To which side is the child rotted? (Answer in Appendix 2) c Schemtic drwing of the rotted lterl film. The ris re visile nd not the spinous process d Lterl rdiogrph of child in, showing these findings nd the posterior opcity (rrow) e Another rotted child with ll of the normlities descried ove. To which side is this child rotted? (Answer in Appendix 2). e

6 20 3 Chest Exmintions in Children Fig Effect of ptient position nd the tue trget distnce Ptient in supine position, with pproximtely 46 in. (c 1.2 m) etween the X-ry tue nd the film. Upper-loe vessels (rrow) re equl in size to those of the lower loe (rrow). The hert is mgnified. There is centrl venous ctheter in plce Ptient is erect nd 6 ft (c 1.8 m) from the X-ry tue. It is difficult to see the upper loe vessels, ut the lower loe vessels re esily seen Tle 3.2. Determining rottion: nswers nd questions Question On the frontl film, re the nterior ris equidistnt from ipsilterl pedicles? Are the medil spects of the clvicles symmetricl in reltion to the midline on the frontl view? Wht is the position of the crin in reltion to the right pedicles on the frontl film? Is one lung lcker thn the other on the frontl view? On the lterl view, re the ris seen posteriorly? Answer No: rotted ptient Yes: stright ptient No: rotted ptient Yes: stright ptient To the left of the right pedicles: ptient is rotted, or nother normlity is present Approximtes the right pedicles: ptient is stright Yes: ptient is rotted, or normlity is cusing loclized difference in ertion No: stright ptient Yes: rotted ptient No: stright ptient

7 Adequcy of Exposure 21 How the Film Ws Otined The third mjor technicl fctor to keep in mind is how the film ws otined. Greter mgnifiction occurs when structures, such s the hert, re frther from the film. When the X-ry em psses through the ptient from ck to front [ posterior nterior (PA) projection], the hert is closer to the film nd is less mgnified. Conversely, if the X-ry em enters the front of the ptient s chest, psses through the ck nd onto the film [n nterior posterior (AP) projection], the mgnified hert nd gret vessels my give the impression of crdiomegly. This is common prolem with portle chest films, which re tken in the AP direction. Another importnt fctor in mgnifiction is the distnce of the X-ry tue from the film. Routinely, portle films re exposed 40 in. (c. 1 m) from the tue, dding to the mgnifiction. Figure 3.6 shows the principles of mgnifiction nd the criteri for recognizing how film ws otined. Adequcy of Exposure Be sure tht the film is properly exposed or the digitl imge is windowed nd leveled properly (Figs. 3.7, 3.8). You cn tell this on the frontl film y exmining the verterl column ehind the hert.if you cn see the detiled spine nd pedicle through the hert nd cn lso see the pulmonry vessels in the peripherl lung, the exposure is correct. If you see only the spine ut not the pulmonry vessels, the film is too drk (overexposed). On digitl imges, the exposure will usully e correct s one cn window nd level the picture. However, on digitl imges, one cnnot tell much out rdition dose (Chp. 2). Fig Tue film distnce nd mgnifiction

8 22 3 Chest Exmintions in Children c Fig Adequcy of exposure This is n entirely lck film, showing tht there hs een too much exposure (overexposure) nd ll of the X-ry ems hve pssed through the ptient to hit the cssette or film nd none were sored y the ptient This is n underexposed exmintion. The film is white, nd you cn rely see the surgicl sutures (rrow) in the sternum nd cnnot see the spine t ll c This is (overexposed) frontl exmintion; properly exposed exmintion is seen in Fig Note how on the poorly exposed film the pedicles cn e seen (rrow), ut you cnnot see peripherl lung mrkings

9 Trps: Unique Antomicl Norml Vrints nd Positions of Tues 23 Fig On the properly exposed films, you cn see oth the pedicles (p) nd the peripherl lung mrkings (rrow). Is the film up correctly? (See Appendix 2) Trps: Unique Antomicl Norml Vrints nd Positions of Tues The chest rdiogrph ccounts for lest 50% of ll peditric imging, nd therefore you must e wre of the norml vrints. The thymus my dominte the medistinl silhouette (see elow). Norml skin folds re frequently seen in young infnts nd must e differentited from pneumothorces (the presence of pulmonry vessels extend into the lck re when there is skin fold; there re no mrkings when there is pneumothorx (see Chp. 4). The centrl cleft of the two posterior neurl rches which hve not fused is often noted (Fig. 3.9). These spinous processes of the spine usully fuse etween the ges of 3 nd 5 yers. Occsionlly one will see clcific densities overlying the right or left thorx on infnt chest rdiogrphs. These re the sternl centers in slightly rotted film (Fig. 3.10). It is importnt to note the position of the tues, clips, sutures, nd monitoring devices. If the child who is intuted is hving unexplined respirtory distress, two views (frontl nd lterl) my help define tue position (Fig. 3.11). Fig Trps Nonfusion of spinous process. On this supine film of 6-month-old infnt, the spinous processes (rrow) of the thorcic vertere re not fused t multiple levels

10 24 3 Chest Exmintions in Children Fig Sternl ossifiction centers As you cn tell y the ris, this ptient is quite rotted. There is nsogstric tue in the esophgus. You should note multiple rounded ony structures projecting over the hert in the right hemithorx (rrows). These re the sternl ossifiction centers, which ecuse of rottion re clerly visile Fig This neonte hs respirtory distress Frontl rdiogrph shows the endotrchel tue in the pproprite position (rrow). However, see the lterl film On this lterl rdiogrph, the endotrchel tue is in the esophgus (white rrow); the irwy (lck rrow) is nterior. Whenever there is question of unexplined respirtory distress, lterl film my e helpful, prticulrly in n intuted ptient

11 Bones nd Soft Tissues 25 Interpreting the Film: The Rdiologist s Circle Anyone cn glnce t peditric chest film, nd with very little trining identify ovious normlities right? Wrong! It tkes most rdiologists yers to get into the hit of reding chest rdiogrph properly. Let s fce it: nyone ordering chest film is going to look t the hert nd lungs, ut rdiologists look first t the nonpulmonry res, i.e., the domen, ones, soft tissues, nd irwy, to e sure tht they do not miss ny normlity (see Appendix 1: Rules for Reding Peditric X-Rys ). Only then does one progress to the medistinum, nd oserves the lungs lst. A good hit to develop is to mke n imginry circle on the film so s to dispense with ll the noncrdiopulmonry res. Begin t the corners nd/or where the ptient informtion is. Be sure when imging on PACS tht ll the ptient informtion nd technicl fctors re displyed (there re options to remove technicl dt). Check the nme, dte, nd especilly the left or right mrker. Nothing is more emrrssing thn missing dextrocrdi with dominl situs inversus ecuse one did not look for the mrker nd therefore put the film up wrong. An esy wy to complete the circle is to go from the nme tg to the mrkers to the ABCS of the film: A=domen, B=ones, C=chest (irwy, medistinum, lungs, nd diphrgm), S=soft tissues. Fig with these clues in mind; on every chest film, look t the domen s if you were reding n dominl film. Bones nd Soft Tissues One cn often see portions of the rms, shoulders, ris, sternum, nd mndile, s well s cervicl, thorcic, nd lumr vertere. Be lert for frctures, congenitl normlities, one destruction, or other signs of disese. It is very emrrssing to miss sent clvicles on chest film ecuse the ones were not viewed systemticlly. This is lso good time to exmine the soft tissues of the neck, thorx, nd domen to detect ny swelling, foreign ody, clcifictions, etc. The soft tissues my revel multiple rtifcts, such s hir rids, uttons, ndges, or redundnt skin folds. Soft tissue swelling or sucutneous clcifictions cn e clues to systemic disese. By now you hve returned, vi your imginry circle, to the cervicl re, nd you re redy to inspect the vertere. Wht normlities do you see in Figs ? Look t the films nd then go to Appendix 2. Adomen Rule No. 1: On every chest film, red the dominl portion s you would red n dominl film.* Evlute the domen (regrdless of how little of it cn e seen) on every chest film, nd note whether the stomch ule is on the left nd the liver on the right. Look specificlly for clcifictions, such s gllstones or pncretic stones. Is the owel distended? Are there ir fluid levels? Is this n erect film? Cn you see free intrperitonel ir or fluid? Now look t * These rules were dopted from Joseph O. Reed, M.D., chief of peditric imging t Children s Hospitl of Michign from 1957 through Throughout this text we include these fundmentl concepts, which were used dily in his teching sessions. (See Appendix 1)

12 26 3 Chest Exmintions in Children c Fig Cn you find the normlity? (Look t the films; then red on) Film of 12-month-old oy. No, the film is not leled incorrectly. The ptient hs dextrocrdi nd dominl situs inversus Correct position of the film c An 11-yer-old girl with lunt dominl trum. Free ir is seen elow the diphrgm. The diphrgm extends cross the midline n impossiility. This is the continuous diphrgm sign. Note how you cn see oth sides of the diphrgm. The ptient ws in motor vehicle ccident nd hd perforted owel d A lterl rdiogrph of sickle cell ptient with lrge hert. Most importntly, did you see the gllstones? d

13 Bones nd Soft Tissues 27 Fig This 13-yer-old girl presented with fever nd pin Fig A 9-yer-old oy with cough

14 28 3 Chest Exmintions in Children Fig A 17-yer-old oy with cough Fig This 12-yer-old presented with cfé u lit spots nd scoliosis

15 Chest (Airwy, Medistinum, Diphrgm, Lungs) 29 Fig A 6-month-old infnt with fever of unknown origin Chest (Airwy, Medistinum, Diphrgm, Lungs) Rule No. 2: Knowledge of ntomy is the key to the correct rdiogrphic dignosis. Airwy The cephlic-most portion of the irwy is the nose nd chonl ir spce. These structures re seen est on CT (Fig. 3.18), ut the rest of the irwy is est nd most conveniently seen on the plin film. The lterl view of the neck is optiml for evluting the suprglottic (supr, ove; glottis, vocl cords) irwy (Figs. 3.19, 3.20). A proper study is otined y ligning the top of the film with the top of the ptient s er. The cephlic-most portion of the irwy is the nsophrynx, which communictes nteriorly with the nres nd merges posteriorly to form the hypophrynx. For ll prcticl purposes, the lower order of the nsophrynx is the hrd plte, soft plte, nd the uvul. The orophrynx (elow the hrd nd soft plte) leds to the ir spces t the se of the tongue, which re the vllecule. Immeditely ehind the vllecule is the epiglottis. The hyoid one is inferior nd nterior to the vllecule. The orophrynx lso merges posteriorly with the nsophrynx to form the hypophrynx. One cn see the pltine tonsils in the lterl wlls of the hypophrynx. Anteriorly, the hypophrynx leds to the lrynx nd ecomes the esophgus inferiorly nd medilly. The pyriform sinuses re the most lterl nd inferior spects of the hypophrynx; their inferior mrgins provide hndy lndmrk for the level of the vocl cords. It is importnt when otining lterl neck exmintion to slightly hyperextend the ptient s hed nd neck. This flttens the redundnt soft tissues in the retrophryngel re ginst the cervicl spine. The child must e stright lterl nd hve ir in the hypophrynx. The frontl rdiogrph is est for viewing the suglottic irwy. The true vocl cords re t the sme level s the tip of the pyriform sinuses. Immeditely elow the glottis is the suglottic region, which is only severl millimeters long nd merges inferiorly into the proximl trche (Figs. 3.21, 3.22). Note tht the irwy is dynmic system nd chnges in clier nd position so tht n isolted, single film my e quite misleding. Nonetheless, n norml configurtion of the irwy should e pursued in the light of the clinicl history. Mgnifiction high-kilovoltge rdiogrphy is noninvsive, useful procedure to delinete the upper irwy, trche, nd mjor ronchi. This technique is most useful for children with stridor, choking, suspected foreign ody, vsculr ring, nd intrtrchel

16 30 3 Chest Exmintions in Children Fig Chonl tresi. In this neworn y there is ony connection etween the vomer nd the lterl pltine one. All these ones hve fused nd this is ony chonl tresi (rrows) Fig The norml irwy, lterl view. (From [1] with permission) mss. It is otined t fluoroscopy so irwy chnges in clier cn e noted. An exquisite view is otined y using Thoreus filter to selectively screen out low-kilovoltge rdition, incresing the exposure kv nd mgnifying the child s irwy (Fig. 3.23). This technique hs, for the most prt, ovited the more invsive trcheogrm, where contrst ws instilled into the trche nd pictures otined. The mgnifiction high-kilovoltge technique cn e used without sedtion nd with reltively little rdition. Rule No. 3: The irwy should e visile on ll norml chest films. Figure 3.24 depicts severl pthologicl sttes of the irwy dignosed y rdiogrphs of the chest or neck. Wht re the normlities, nd wht re the diseses? See Appendix 2. The prmeters to evlute the irwy, e it extror intrthorcic, re ptency, position, nd size. One should see the entire irwy, from the orl nd nsl phrynges to the right nd left min-stem ronchi. The wlls should e prllel nd smooth. However, uckling of the trche to the right in the lower neck nd upper thorx is norml in n infnt. The in- trthorcic irwy is not midline structure (the crin overlies the right pedicles). Wht normlity cn you detect in Fig. 3.25? Medistinum The medistinum is composed of the thymus, trche, hert, gret vessels, esophgus, lymph nodes, nd neurl elements. It cn e seprted into the nterior, middle, nd posterior comprtments (Fig. 3.26). In exmining the medistinum, rememer: Rule No. 2: Knowledge of ntomy is the key to correct rdiogrphic dignosis. In the medistinum, look for position, size,nd contour of the individul components. The initil exmintion of the medistinum is est ccomplished y the plin film. However, for most normlities or questions of normlity, MR or CT is utilized. Therefore in this discussion of the medistinum plin film findings re followed y cross-sectionl imging.

17 Chest (Airwy, Medistinum, Diphrgm, Lungs) 31 Fig Norml (nd lmost norml) lterl neck exmintions in 2-yer-old, n 8-yer-old, nd 10-yer-old This 2-yer-old is in the neutrl position. Using our sic concept of looking t the entire film, we note tht the sell turcic (s) is norml. The ptient hs denoid tissue (), which should e present y 6 months of ge, nd lso pltine tonsils (t). The ptient hs undnt ir in the hypophrynx nd one cn see the retrophryngel soft tissue spce (ehind the hypophrynx nd in front of the spine) is quite norml. The vllecul t the se of the tongue (v), hyoid one (rrow), epiglottis (rrowhed), nd the lryngel ventricle re norml. There is uckling of the proximl trche s expected in this ge group A 9-yer-old child in which we see similr ntomy, perhps etter defined. The denoid tissue () is somewht lrger nd is encroching upon the nsl ir pssge. rp, retrophryngel spce; lv, lryngel ventricle. The pltine tonsils re lso lrge c A 10-yer-old child. The sell (s) is norml. The denoids () do not nrrow the nsl ir pssge (norml) c

18 32 3 Chest Exmintions in Children Fig Schemtic drwings of the frontl irwy during vrious phses of respirtion nd phontion A, quiet rething; B,phontion; C, closed glottis. (From [1] with permission) c Fig Three frontl rdiogrphs ( c) corresponding to the schemtic view in Fig. 3.21: quiet rething, phontion, c closed glottis

19 Chest (Airwy, Medistinum, Diphrgm, Lungs) 33 Fig e. Legend see p. 34 c d

20 34 3 Chest Exmintions in Children e Fig A 1-yer-old oy with stridor Frontl rdiogrph shows the lungs to e of norml volume nd the hert of norml size. The thorcic irwy is clerly demonstrted, ut there is liner opcity within the irwy in the cervicl region Mgnifiction high-kv film showing the foreign ody. A piece of eggshell ws lter removed. (From [2] with permission) c e Three views of mgnifiction high-kv technique in 1-yerold with stridor. There is nrrowing nd penciling of the irwy (rrow) on ll films. This ws fixed chnge, ut on clinicl followup severl weeks lter the ptient ws not longer stridorous nd the irwy ppered norml. This represents inflmmtory chnges (lryngotrcheoronchitis croup) Fig Wht ntomicl normlity cn you see in these two seprte exmintions lterl chest film nd lterl neck film in nother child? (Answer in Appendix 2)

21 Chest (Airwy, Medistinum, Diphrgm, Lungs) 35 Fig A 6-month-old infnt with cough Frontl rdiogrph shows the crin pushed to the left. There is ulge on the right side of the irwy. Cn you see norml ortic rch on the left? This is right ortic rch to the right of the trche with right descending ort (rrow) to the right of the spine. This child hs congenitl hert disese, tetrlogy of Fllot. Mny children (pproximtely one-third) with this disese hve right ortic rch Norml uckling of the irwy in n infnt Fig Medistinum Anterior, the spce in front of the hert nd gret vessels; middle, the spce etween the nterior nd posterior medistinl components, including hert, irwy, esophgus, nd lymph nodes; posterior, everything ehind line connecting the midportion spects of the vertere, including the vertere, neurl elements, nd prspinl lymph tissue. (See Msses nd Pseudomsses for msses typicl of these res.) Some definitions egin the posterior medistinum with the nterior spect of the verterl ody

22 36 3 Chest Exmintions in Children Thymus One of the mjor fctors tht mkes peditric chest X-rys difficult to evlute is the thymus. It is sid tht he who msters the thymus hs mstered 90% of peditric chest films, ecuse this glnd cn simulte crdic enlrgement, lor collpse, pulmonry infiltrtes, nd medistinl msses. The thymus is prominent in some children until 4 5 yers of ge. It strts to ecome prolem when it is still prominent in children over the ge of 5. The thymus is lwys nterior in position, which is why it is difficult to dignose right hert enlrgement in younger child sed on fullness of the nterior medistinum. Since it is such n nterior structure, it is suject to wide vritions in shpe nd size on the frontl chest rdiogrph; even with the slightest degree of rottion, the thymus my oscure lmost the entire right or left lung. To void errors in interprettion, check the degree of inspirtion nd the position of the ptient efore deciding out unusul densities (Fig. 3.27) (see Technicl Fctors, ove). Thymic size is mjor re of concern. The thymus my occupy the entire nterior thorx, extending down to the diphrgm nd out to the lterl thorcic wll. It usully ppers smller s the child gets older, ut the thymus weighs most in n dolescent. Thymic remnnts cn remin even into dulthood. It is unique orgn which lso shrinks during periods of stress. The contour of the thymus is wvy ecuse it insinutes itself etween nterior ris. It is soft orgn nd does not push other medistinl structures. Occsionlly, fluoroscopy or ultrsound is necessry to decide whether the contour of medistinl mss is indeed wvy nd nterior, consistent with thymus. More often, however, if n normlity is suspected in the medistinum, cross-sectionl imging (MR or CT) is performed. Both tests require the young ptient to e sedted. CT, of course, entils rdition exposure, nd the ptient lso receives n intrvenous contrst gent, ut it hs the dvntge of showing clcium nd, if pertinent, the lung prenchym (see elow). For proper evlution of the medistinum with CT, contrst medi is essentil. With contrst medi, the vessels nd hert light up (turn white enhnce ). Thus, nything not enhnced must e explined y norml ntomicl structures or else it is norml. MR hs the dvntge of presenting imges in multiple plnes (coronl, sgittl, xil, nd olique) nd most precisely shows extension of tumor into the spinl cnl. MR differentites tissue chrcteristics to greter extent thn CT, ut it is poor for clcium nd lung prenchym. Since either test my e etter depending on the pthology, imges of oth modlities re presented (Figs. 3.28, 3.29). These imges help define msses, lymph nodes, nd errnt vessels etween nd round norml structures. An importnt finding in the medistinum nd soft tissue is dventitious ir it occurs in pneumomedistinum or cn descend down from ove s in hypophryngel perfortion (Fig. 3.30).

23 Chest (Airwy, Medistinum, Diphrgm, Lungs) 37 c Fig Thymus Frontl rdiogrph shows ll the prmeters of film tken during expirtion. If you re not cquinted with these criteri, you my interpret this film s showing n infiltrte in oth lungs. (See Tle 3.1 nd Fig. 3.2 for criteri estlishing tht the film is tken during expirtion.) Note tht the spinous processes re not fused With good inspirtory effort, sme child shows tht the infiltrte is relly thymus which is quite prominent on the right. Notice the thymic sil sign (rrow). c In this rotted film, one cn see the effect of the thymus in the right upper thorx. A nsogstric tue is in the stomch d A more rotted film shows gin how the thymus cn msquerde s prenchyml opcity. This ptient hs centrl vsculr line in the right trium d

24 38 3 Chest Exmintions in Children c d e f g Fig Norml contrst-enhnced CT of the medistinum (xil projection). Rememer the vessels in the hert light up Most cephlic section revels the sternum nteriorly. The superior ven cv (S) nd innominte vein (I) re clerly visile. The left suclvin rtery is seen (rrow) A next lower section shows the ortic rch on the left side (A) c Proceeding inferiorly, the descending ort (D) is noted. Note the nonenhnced thymus of tringulr shpe nteriorly. This occurs in children over 5 yers of ge. Before 5 yers of ge, the thymus is rectngulr d A section through the min pulmonry rtery (P) nd its right (RP) nd left (LP) rnches. This section is just elow the crin nd the left min-stem ronchus is seen ove the descending ort (D) e This section is t the level of the left trium (LA) f A section showing the ventriculr septum (S) nd oth ventricles g The most cephlic section of the liver showing the joining of the heptic veins (HV) to the interior ven cv (C)

25 Chest (Airwy, Medistinum, Diphrgm, Lungs) 39 c d e Fig k. Legend see p. 40 f

26 40 3 Chest Exmintions in Children g h i j k Fig MR of the medistinum (xil, coronl, nd sgittl sections). Rememer: lck is flowing lood The cephlic-most section revels the rectngulr, homogeneous thymus nteriorly eneth the sternum nd in front of the ortic rch (A). The verterl ody (V) nd durl sc (rrow) re seen posteriorly on ll the sections The next section is t the level of the min pulmonry rtery (P). This ptient hs corcttion of the ort. Note the smll descending ort c The next cudd plne is t the level of the left trium (LA) d Section through four chmers of the hert e Most nterior coronl section showing thymus (T) nd right trium (RA) f Next posterior section through the scending ort (AA) g, h Section through the trche (T) nd left trium (LA) i Posterior section showing the verterl odies j Olique midline sgittl section showing the ortic rch (AA). See the discrepncy etween the ortic rch nd proximl descending ort k Sttic sgittl scn of cine MR imging with the computer-enhnced lood ppering white. Note the descending ort (rrow)

27 Chest (Airwy, Medistinum, Diphrgm, Lungs) 41 Fig Medistinl nd pericrdil ir Frontl exmintion shows ir (lck) in oth shoulders (rrows), xill, chest wll, nd in the medistinum. There is seprtion of the ortic kno from the pulmonry rtery (rrowhed). In this instnce, there is oth ir in the medistinum, s seen in the shoulders, nd ir in the pericrdium, s seen y the seprtion of the pulmonry rtery nd ort Lterl view shows ir (rrow) nterior to the hert nd in the medistinum Hert The hert must lso e evluted for position, size, nd contour. Its position is normlly in the left hemithorx with smll right thorcic order. The ppernce of the hert on the frontl film depends gretly on the degree of inspirtion nd on the size of the thymus. For these resons the lterl roentgenogrph is importnt s the ir spce ehind the hert nd the position of the nterior mrgin of the trche ply mjor dignostic role. There re two methods for using the lterl film to evlute hert size. In the first, perpendiculr line drwn from the crin to the diphrgm should not intersect the hert. A second method is to extend line prlleling the nterior wll of the trche inferiorly to the diphrgm. In this instnce, the line should not intersect the hert nor should the line e pushed ck to hit the spine ove the diphrgm. Both methods work est on nonrotted lterl films. Rememer, n enlrged hert pushes the trche ck, s do other medistinl normlities. Therefore if frontl film shows questionle crdic enlrgement, look t the lterl! If the lterl film is norml, the hert size is norml (Fig. 3.31). Rule No. 4: A mss must e seen in two plnes. If the hert is relly lrge, it must pper lrge in two plnes, oth frontl nd lterl. The contour of the hert on plin films, in our experience, is not helpful in determining the specific nture of congenitl nomlies. Echocrdiogrphy, MR, nd crdic ctheteriztion re more ccurte methods of dignosing congenitl defects. Nonetheless, evluting the contour of the hert in n older child where the thymus is smller cn e vlule. In young children the left tril ppendge is not prominent ulge on the left side ecuse it is usully oscured y even smll thymus. The pulmonry rtery, however, my e prominent normlly in dolescents (especilly girls). Pulmonry vsculr chnges, on the other hnd, my give clue to the exct nture of the crdic disese. Normlly one sees pulmonry vessels in the hil nd the middle third of the lungs ut not in the more peripherl portion. Signs of incresed rteril flow include: () enlrged centrl vessels, () enlrged vessels in the medil third of the lung, nd (c) on the erect film, equliztion of vessel size etween upper nd lower loes.venous congestion ssocited with clinicl findings of congestive hert filure cn

28 42 3 Chest Exmintions in Children c d Fig Evlution of crdic enlrgement on lterl film Frontl view of the chest shows the hert to e enlrged. There re indistinct vessels. These two findings suggest congestive hert filure The trche nd crin re esily seen on the lterl film c, d Using the crinl line (c) or the nterior trchel line (d) demonstrtes crdiomegly. In this instnce, oth prmeters re seen the hert extends ehind the imginry line nd the line hits the spine ove the diphrgm e see p. 43

29 Chest (Airwy, Medistinum, Diphrgm, Lungs) 43 Gret Vessels The gret vessels tht re esily identified re the inferior ven cv (on the lterl view) nd the ort (on the frontl film). The position of the trche is the key to locting the ortic rch (see Fig. 3.25). A right ortic rch is often ssocited with congenitl hert disese or vsculr ring which presses on oth the irwy nd the esophgus. For this reson, py specil ttention to the trchel ir column nd the ulges long either side. The right nd left pulmonry rteries re esily identified, nd the min pulmonry rtery is one of the moguls (umps) of the left hert order (Fig. 3.32). Wht is the unusul dilttion ove the right min-stem ronchus in Fig. 3.33? MR is super for defining the side of the rch s well s normlities of the gret vessels (Fig. 3.34). See Appendix 2. e Fig (continued) e Norml nterior trchel line e indicted y: () loss of distinct vessels t the ses (interstitil edem), () lveolr filling (pulmonry edem), or (c) right-sided pleurl effusion. Rememer: lnguge here is importnt! Overcircultion, incresed rteril flow, nd incresed vsculrity ll suggest left-to-right shunt. Congestion nd pulmonry venous distension suggest congestive hert filure. It is much more difficult to detect decresed pulmonry vsculrity. Correlting pulmonry vsculrity with hert size nd the clinicl sttus of the ptient (cynotic vs cynotic) is frequently helpful in determining specifics of congenitl hert disese. Note: Overcircultion is usully ssocited with crdiomegly. If you suspect overcircultion ut the hert ppers norml, something is usully wrong with your oservtions. Crdic MR is ecoming n extremely importnt imging modlity. Aside from precise ntomy, it offers functionl informtion out pulmonry vein nd myocrdil lood flow nd myocrdil ischemi. Esophgus The esophgus is nother structure seen in the medistinum. It is posterior to the trche nd my contin ir in younger children. An ir fluid level in the esophgus, however, is lwys norml. Since esophgel prolems my mnifest s respirtory symptoms, the rium swllow is vlule dignostic exmintion in cses of unexplined respirtory disese (Fig. 3.35). Rule No. 5: An esophgrm must e performed on ny child with unexplined respirtory disese.

30 44 3 Chest Exmintions in Children Fig Moguls (umps long hert order) Schemtic drwing of the impression of vrious vsculr nd crdic structures in the medistinl silhouette, c A young child with pericrdil effusion. This ws dignosed y echocrdiogrphy. The plin film, however, is reveling in tht the crdic silhouette is lrge ut none of the norml moguls re seen. Note how fr ck the crdic silhouette is on the lterl view c Fig Wht is the unusul dilttion (rrow) ove the right min-stem ronchus?

31 Chest (Airwy, Medistinum, Diphrgm, Lungs) 45 c Fig Vsculr ring Plin film exmintion shows mss (m) to the right of the irwy with the crin to the left of midline Brium swllow in the frontl projections shows the impression on the right nd left side of the esophgus (rrows) c Coronl MR revels two circles, one to the right nd one to the left of the trche (t). These circulr impressions re the right nd left rches d A more posterior coronl MR section shows the two rches joining nd descending. This is doule ortic rch e g see p. 46 d

32 46 3 Chest Exmintions in Children e f g Fig e g (continued) e Another child with doule ortic rch. The crin (c) is over the left pedicles f The lterl film shows nterior owing of the trche (rrow) g Lterl film of rium swllow in this child showing the mss impression ehind the esophgus nd cusing slight owing nd nrrowing of the irwy

33 Chest (Airwy, Medistinum, Diphrgm, Lungs) 47 Fig Reltionship etween the esophgus nd the trche Norml lterl esophgrm. Note the trche nd esophgus nd their reltionship Lterl view of child with esophgel stricture c Lterl view fter most of the rium hs pssed into the stomch. Note how the dilted esophgus (now filled with ir) ows nd compresses the trche (rrow) c

34 48 3 Chest Exmintions in Children Fig Enlrged medistinl nd hilr nodes This 8-month-old hd tuerculosis. There is enlrgement of the right hilum nd the right ronchus is nrrowed y multiple medistinl nodes Fig Lor nd fissure ntomy Lymph Nodes Medistinl lymph nodes re not visile on plin films unless they re enlrged (Fig. 3.36). Lymph nodes re well seen on CT nd MR. Lungs Let s review the ntomy of the lungs (Fig. 3.37). The upper nd middle right loes re seprted y the minor fissure frequently seen in norml chest rdiogrph. The mjor fissure seprtes the right lower loe from the right middle loe nd upper loe. The left mjor fissure is more verticl nd posterior. These cn often e seen on the lterl film. The pulmonry vessels re esily seen rnching in the inner two-thirds of the lung. Most of the time the right hilum is lower thn the left; it is never higher. The mjor ronchi re seen centrlly ecuse of the opcity of the medistinum surrounding these ir-filled tues; they cnnot e seen peripherlly. There re few visile lung mrkings in the peripherl third of the lung, especilly in young children. Normlly the pleur is not visile. The hemidiphrgms chnge contour with respirtion ut re nicely dome-shped on oth frontl nd lterl films. Becuse the lungs re ir-filled, they offer shrp contrst to the soft tissue opcity of the hert nd diphrgm, whose mrgins re quite shrp (see Fig. 3.1). If the mrgins re fuzzy or oliterted, the lung djcent to these mrgins is norml (the silhouette sign). Fine detil of lung ntomy is seen est with CT (Fig. 3.38). Routine CT is performed t 5- to 10-mm intervls nd reconstructed with one nd stndrd lgorithms. High-resolution CT is performed t thin sections (1- to 2-mm) nd with one lgorithm. We view oth with lung windows. High-resolution CT demonstrtes the lung detil of the secondry loules with their concomitnt vessels nd ronchioles. The ronchioles nd rteries re centrl with the interloulr septum composed of connective tissue nd pulmonry veins peripherlly plced (Fig. 3.39). High-resolution CT fcilittes dignosis of ronchiectsis, diffuse lung disese, defining the full extent of pulmonry disese s well s explining worrisome findings on the plin film. It is used for detection of pulmonry metsttic disese when stndrd CT is equivocl.

35 Hyperexpnsion 49 Fig Antomy s seen on high-resolution CT This shows the ility of CT to visulize smll structures within the lung. (From [2] with permission)

36 50 3 Chest Exmintions in Children c d Fig High-resolution CT. This is the ntomy of the secondry pulmonry loule Antomy of the secondry pulmonry loule Norml ppernce in n isolted lung preprtion (rrows, pointing to smll ronchus). (, from [3] with permission) c Norml ppernce in 10-yer-old child d High-resolution CT in teenger with hypogmmgloulinemi nd lymphoid interstitil pneumonitis. Note the effects on the secondry loule Common Pthologicl Conditions Hyperexpnsion Hyperexpnsion of the lungs results from ir trpping, i.e., the ir cnnot exit s rpidly s it enters. This my e cused y ny functionl or orgnic irwy ostruction. Logiclly, hyperexpnsion is mnifested y flttening or inversion of the diphrgm, widening of the ri interspces, nd lrger cler spces in front nd in ck of the hert. The hert itself my e compressed nd reduced in trnsverse dimeter. The lungs my pper drker thn norml, ut check tht the film ws not overexposed (see Fig. 3.3). In generl, it looks s if the child took very deep reth when he clerly seems too young to hve

37 Hyperexpnsion 51 Fig A 3-yer-old who strted choking fter eting penuts Inspirtory frontl film hs sutle chnges: the right lung is hyperexpnded nd lcker thn the left, lthough there is no medistinl shift Expirtory film revels tht ir did not leve the right lung; it remins trpped during the expirtory phse of respirtion. The medistinum is shifted to the left (the left lung hs gone through expirtion properly) c Two dys fter penut ws removed from the right min-stem ronchus the expirtory film shows no difference in ertion c followed the technicin s instructions. The ir trpping is involuntry nd must e seen on oth frontl nd lterl views to e sure this finding is rel. When hyperexpnsion occurs chroniclly, cor pulmonle my result. Hyperexpnsion my e unilterl or ilterl. Common cuses of ilterl hyperexpnsion re () sthm, () ronchiolitis, nd (c) cystic firosis. Isolted hyperexpnsion of one or two loes unilterlly is commonly found in children who hve spirted foreign ody or hve hilr nodes compressing the ronchus (Fig. 3.40). Becuse of unilterl hyperexpnsion, the medistinum my e shifted. In ddition, unilterl hyperexpnsion my result from telectsis or collpse of the contrlterl segment of lung. Recognizing unilterl hyperexpnsion of the lung is extremely importnt in peditrics ecuse children frequently spirte foreign mteril.

38 52 3 Chest Exmintions in Children Rule No. 6: In unilterl hyperexpnsion of the lungs, you must see how the ir moves. Air must move in nd out of ech lung. Medistinl position is criticl to this determintion. The movement of ir within lung cn e visulized y vrious procedures, such s () inspirtory nd expirtory rdiogrphs (look for shift of medistinl position), () fluoroscopy of the chest (look for shift of medistinl position nd ppropriteness of diphrgmtic motion), nd (c) decuitus films (the down side is the expirtory side of the rdiogrph). With these mneuvers one should e le to see which side is norml, i.e., ir in the norml side does not move ppropritely (see Fig. 3.40). If there is too much ir in one hemithorx, e sure there re lung mrkings within the re; one my e overlooking pneumothorx. It is mndtory to identify the viscerl pleurl mrgin. Lor Collpse It is often helpful to think of the loes of the lungs s eing ttched t the hil s if they were fn. When these loes collpse, they still retin their hilr ttchment, nd the other loes often expnd to compenste. The ptterns of the lor collpse re identified in two wys: y seeing the collpsed loe in recognizle pttern, nd y noticing sutle shifts of intrthorcic structures such s the fissures etween loes of the lung nd loss of norml roentgenologicl orders (silhouette sign) (Figs. 3.41, 3.42). Five questions should e sked when n opcity is seen tht ppers to e lor collpse: To which side is the medistinum shifted? In wht directions re the mjor nd minor fissures devited? Wht norml structures re silhouetted? Is the hilum shifted up or down? Is the diphrgm elevted (see Figs. 3.41, 3.42)? A common cuse of lor collpse in children is mucus plugging in postopertive nd sthmtic ptients. Alwys look for foreign odies y crefully exmining the right nd left min-stem ronchi. Msses such s lymph nodes (due to tuerculosis, other infections, or lymphom), or extrinsic msses such s ronchogenic cysts, cn lso cuse lor collpse. c d e Fig Lor collpse. Note the shifts of the vrious fissures. The lckened re nd rrows denote the position of collpse s opposed to the stndrd position seen in Fig Right upper loe collpse Right middle loe collpse. The hert mrgin is oliterted c Right lower loe collpse d Left upper loe collpse. The mjor fissure moves nteriorly e Left lower loe collpse

39 Lor Collpse 53 Fig Exmples of lor collpse Frontl film showing right upper loe collpse with elevtion of the minor fissure (rrow), c Frontl rdiogrph showing oscurtion of the right hert order, collpse of the middle loe, nd shift of the medistinum towrd the right. The lterl film shows the wedge-shped collpse overlying the hert d, e Right lower loe collpse. The right hert order is mintined ut, s seen on the lterl film, the opcity is posterior nd the mjor fissure is depressed posteriorly (rrow). The hert mrgin is norml f h see p. 54 c d e

40 54 3 Chest Exmintions in Children g f Fig (continued) f, g Left upper loe collpse. Note tht the hert mrgin is quite irregulr nd not well seen. The mjor fissure (rrow) is nteriorly displced nd there is opcity nteriorly h Left lower loe collpse. The hert is no longer trnsprent nd the mjor fissure is shifted medilly nd denotes n re of opcity from the spine to visuliztion of the fissure (rrows) h Chnge in Pulmonry Densities An opcity is represented y the imge ppering too white, nd lucency y its ppering too lck. An opcity in the lung my e cused y () pneumonic consolidtion, () telectsis, (c) neoplsm, or (d) loclized collection of fluid. Sometimes the cuses of opcities re indistinguishle. In fct, two processes often re coexistent. When discussing this prolem with collegues, ewre of the word infiltrte. This hs come to men pneumonic process, ut some rdiologists understnd it to men telectsis or edem. The hert nd liver re trnsprent orgns, i.e., you cn see through them nd visulize the norml rnching pulmonry vessels (Fig. 3.1). If you cnnot see this phenomenon, there is opcity present (Fig. 3.43). Rule No. 7: The hert nd liver re trnsprent orgns. Opcities within the lveolr spce frequently show ir ronchogrms. These occur when ir within the ronchi is seen ginst ckground of irless lung or fluid-filled lveoli. Most lveolr opcities re confluent nd lrger thn individul vessels. Any mteril, such s pneumonic consolidtion or fluid from congestive hert filure, my e mnifest y lveolr ir-spce opcity. In diseses such s virl pneumoni opque discrete liner streks re found. These incresed interstitil mrkings represent perironchil thickening nd telectsis: wht is commonly termed the rdiologicl dirty lung, common finding in ptients with sthm. Rememer, the dirty lung is sign, not specific disese!

41 Chnge in Pulmonry Densities 55 c Fig The hert nd liver re trnsprent orgns A 2-yer-old with fever nd cough. One cn see vessels through the liver nd through the most left lterl contour of the hert (rrows). However, medilly, there is lrge opcity consistent with left lower loe pneumoni (sterisk), c A 3-yer-old with fever nd tchypne. There is sutle opcity ehind the left hert on the frontl film. The lterl film, however, shows lrge opcity (rrow) posteriorly mking the verterl ody look whiter thn the ones ove. This is good sign on the lterl tht there is opcity d The sme child t follow-up exmintion: note how lck the vertere pper without the lower loe opcity d Lor pneumoni cn silhouette the medistinum, mimicking lor collpse (Fig. 3.43). However, there is no medistinl shift of the sme mgnitude, nor is there significnt loss of lung volume ssocited with chnge of position of the fissures. The most overdignosed (nonexistent) pneumonis re: right lower loe pneumoni t the medil lung se, often cused y pulmonry rteril rnches seen on film tken with poor inspirtion, mking the hilr vessels stnd out. Be creful efore dignosing perihilr infiltrte on rotted film! Be leery of opcities in the perihilr regions nd the right lower loe. A clue is tht if upon close inspection of the film it ppers tht the opcity in the right lower loe is relly individul white lines, it proly is not pneumoni. The most overlooked

42 56 3 Chest Exmintions in Children c d Fig Unusul pulmonry opcities Round pneumoni. The frontl chest film shows right upper loe rounded opcity tht might, t first glnce, e mistken for tumor or metstsis. Antiiotic therpy resulted in susequent norml exmintion Another child with right lung round opcity. This too proved to e round pneumoni. Most round pneumonis re cused y streptococcl orgnisms c Loculted pleurl fluid. This child hd unexplined fever nd cough for 2 weeks fter ntiiotic therpy for pneumoni. Chest films show n ellipticl density on the right. Note how it conforms to the position of the minor fissure. This is chrcteristic of loculted effusion (in this cse, infected fluid) in the fissure d Lterl film of nother child with loculted pleurl fluid in the posterior portion of the mjor fissure pneumoni is tht found in the left lower loe (see Fig. 3.43). This is esily recognized when you rememer tht the hert should hve the sme density throughout. It is trnsprent. Be wre of chnges in opcity nd density! Loss of pulmonry rtery visiility or sudden chnge from gry to white in ny portion of the hert should mke you suspicious of retrocrdic pneumoni. When reding chest film, trin yourself to look through things, i.e., the hert nd liver. Also, keep your eye on the left hemidiphrgm; it should e seen s clerly s the right.any disruption my men djcent pneumoni or telectsis (silhouette sign).

43 Msses nd Pseudomsses 57 Fig A 16-month-old with cough Frontl chest rdiogrph shows the medistinum shift to the right nd owel loops compressing the left lower lung Brium ws given, confirming the intrthorcic loction of the stomch nd smll owel. At surgery there ws n intct diphrgm, ut it ws very thin, consistent with lrge eventrtion. When the eventrtion is this lrge, it cts s mss cusing the sme symptoms s diphrgmtic herni Msses nd Pseudomsses Commonly mss in the lungs of children is in fct pseudomss cused y the round pneumoni (Fig. 3.44). This type of opcity is sometimes so perfectly round tht it simultes neoplsm. Approprite tretment is given, nd follow-up films re otined fter 15 dys to document whether the mss disppers. Another pseudomss is cused y loculted fluid in the fissure. Often this fluid hs terdrop shpe nd conforms to the ntomy of the fissure; the opcity is often shrply demrcted for one-hlf to three-qurters of its orders (see Fig. 3.44). A common juxtdiphrgmtic pseudomss is due to prtil eventrtion thinning of the muscles of the diphrgm; it is most often seen on the right s ump on the diphrgmtic surfce. Such phenomenon is usully symptomtic nd does not require therpy, ut lrge eventrtion cn ct s diphrgmtic herni, cusing medistinl shifts (Fig 3.45). True primry lung neoplsms re uncommon in children. The most common ones re extensions of medistinl structures or re cused y defects of the diphrgm nd re in fct extrpulmonry (Fig. 3.46). It is pproprite, then, to discuss medistinl msses in this ctegory. These msses rise in ny of the three components of the medistinum. The most common posterior medistinl mss is neurogenic tumor such s neurolstom, gnglioneurom, or neurofirom. The hemidiphrgm inserts posteriorly t the L1 2 level; therefore, posterior silr intrthorcic medistinl mss my msquerde s n dominl mss. Rememer the norml inferior extent of the thorcic cvity. If the ris re seprted, the posterior medistinl mss is in the thorx. Middle medistinl msses re most commonly of lymphoid origin (e.g., lymphom), ut lesions of ny of the other structures of the middle medistinum such s esophgel dupliction my occur. The most common nterior medistinl msses re terrile lymphoms, tertoms, nd thymoms (in children ged over 10 yers). True prenchyml msses re frequently due to metstsis such s tht from Wilms tumor (Fig. 3.47). Congenitl msses found in the neonte re discussed in the next chpter (Chp. 4). The outline elow is useful summry of the etiology of medistinl msses: Anterior medistinum (the four T s nd C) Thyroid (ectopic thyroid is often mentioned, never seen!) Terrile lymph node enlrgement y either infection or mlignncy Tertom Thymom Cystic hygrom

44 58 3 Chest Exmintions in Children Fig Medistinl mss This 10-yer-old hs widened medistinum. He is too old to hve lrge thymus nd, in fct, hs n enlrged right hilum with prtrchel denopthy (rrow). The sucrinl region is lso too white when compred to the rest of the hert Lterl roentgenogrph opcity the density in the middle medistinum common presenttion for lymphom (rrows). There is contrst mteril in the esophgus Fig Metsttic lung disese Scout film prior to CT in this 3-yer-old who hd Wilms tumor removed 7 months previously. There re multiple rounded opcities in the chest CT revels multiple lung metstses

45 Pleur 59 Fig Pleurl effusion, Erect frontl () nd lterl () view of ptient with nephrotic syndrome who is 5 yers old. The silhouette sign is present s the left hert mrgin is oscured. Note the distnce etween the stomch nd the pprent diphrgm on the left side (rrows). The diphrgm should e closely pplied to the stomch nd therefore this could not e diphrgm ut is fluid eneth the lung nd ove the diphrgm supulmonic effusion. There is nother crdinl sign of supulmonic effusion on the right side. The highest point of the diphrgm is quite lterl (rrowhed). This is the shpe of the ottom of the lung nd there is fluid elow the lung nd ove the hemidiphrgm. On neither side do we relly see the diphrgm. It is importnt to note tht the usul pleurl rection is n opcity trcking long the lterl chest wll. There is very smll lterl component on the right side nd much lrger lterl component on the left side. The lterl view shows seprtion of the stomch nd diphrgm s well s opcity posteriorly Middle medistinum (n normlity for ech orgn) Esophgus: dupliction cysts Gret vessels: neurysml dilttion Hil: enlrged lymph nodes (leukemi, lymphom, tuerculosis, etc.) Trche: ronchogenic cysts Pericrdium: cyst Posterior medistinum (T, E, N) Tuerculosis (Pott s disese) or ny spinl infection Extrmedullry hemtopoiesis (lmost lwys in dults) Neurl tumors: neurolstom, gnglioneurom, neurofirom, neurenteric cyst Tips when viewing medistinl msses include: Middle medistinl msses silhouette the hert order nd ort. Posterior medistinl msses my spred ris or cuse verterl chnges. Pleur Pleurl rection (effusion or thickening) is est indicted y n opcity etween the erted lung nd ri order (Fig. 3.48). Thickened pleur, loculted pleurl fluid, nd empyem pper similr rdiogrphiclly nd my not e differentited y norml rdiogrphic techniques. Decuitus films demonstrte free-flowing fluid ut my not show movement of loculted pleurl fluid, viscous empyem, or thickened pleur. An excellent wy to detect smll mounts of fluid or limited pleurl thickening not visile on the frontl film is to look crefully t the posterior lung sulci on the lterl film. Then check the thickness of the pleurl line in reltionship to ech ri; it should e snug ginst the ri. Fluid cn lso ccumulte eneth the inferior surfce of the lung nd cn simulte n elevted hemidiphrgm. Such collections re clled supulmonic effusions nd re recognized y the lterlly shifted diphrgmtic dome (see Fig. 3.48). The most common cuse of pleurl effusion in children is infection, nd lmost ny infection cn cuse smll pleurl effusion. Pleurl effusions re lso frequently seen in ptients with congestive hert filure (if unilterl, lwys on the right) nd chronic renl disese. In difficult cses enhnced CT cn differentite pleurl disese from effusion or prenchyml disese (Fig. 3.49). Ultrsound cn often e used s well to find fluid for dignostic tps.

46 60 3 Chest Exmintions in Children c Fig Empyem Chest rdiogrph in this 32-month-old with fever nd respirtory signs revels lrge right opcity with convex ppernce towrd the lung (rrows). This opcity hs n ellipticl type configurtion nd suggests mss or loculted effusion Decuitus film with left side down (see fluid level in stomch) shows the opcity does not move c CT ws performed to show the split pleurl sign. There is enhncement of the prietl nd viscerl (rrow) pleur with low-density fluid etween them. This is infected loculted fluid Summry A thorough rdiogrphic work-up should include the following, in order of priority: Good erect, nonrotted inspirtory frontl nd lterl chest films Inspirtory nd expirtory films (if foreign ody is suspected, there is persistent hyperexpnsion or telectsis ) nd/or fluoroscopy of the chest to oserve medistinl shift nd diphrgmtic excursion (decuitus films my help) Specilized mgnifiction high-kv films of the irwy, if the ir pssge itself needs evlution An esophgrm in ny unexplined irwy disese MR or CT for medistinl msses High-resolution CT for complete work-up of unusul or questionle pulmonry prenchyml normlities Rememer, the chest rdiogrph cn e very tricky thing. It is esy to get seduced y ovious pthology such s mss opcity, lrge hert, or lrge pleurl effusion. You must resist the tempttion to descrie the ovious normlity nd force yourself to do routine, orderly scn of the entire chest film nd not e seduced y the ovious lesion. This method will help trin you to spot more sutle findings, such s ri frcture. A convenient

47 Summry 61 Fig A child with cute onset of respirtory distress. (See Appendix 2) Fig Chronic lung disese. (See Appendix 2) wy to red systemticlly is to evlute the technicl fctors of lung volume, ptient position, nd the wy the film ws exposed. Use the rdiologist s circle nd ABCS: A=domen, B=ones, S=soft tissue, nd C=chest (irwy, medistinum, lungs, nd diphrgm). Now evlute Figs Approch ech one systemticlly nd descrie the normlities you see. The nswers re in the Appendix 2.

48 62 3 Chest Exmintions in Children c Fig A child with wheezing. (See Appendix 2) d References nd Further Reding 1. Slovis TL, Hller JO, Berdon WE, Bker DH, Joseph PM (1979) Noninvsive visuliztion of the peditric irwy. Curr Prol Dign Rdiol 8: Nidich DP, We WR, Mueller NL, Krinsky G, Zerhouni EA, Siegelmn SS (1998) Computed tomogrphy nd mgnetic resonnce of the thorx, 3rd edn. Lippincott- Rven, New York 3. We WR, Mueller NL, Nidich DP (1996) High-resolution CT of the lung, 2nd edn. Lippincott-Rven, New York 4. Kuhn JP, Slovis TL, Hller JO (eds) (2003) Cffey s peditric dignostic imging, 10th edn. Mosy, Phildelphi 5. Newmn B (ed) (1999) Imging of medicl disese in the neworn lung. Rdiol Clin North Am 37: Boiselle PM (ed) (2003) Multislice helicl CT of the thorx. Rdiol Clin North Am 41: Slovis TL (1977) Noninvsive evlution of the peditric irwy: recent dvnce. Peditrics 59:872